Most basin faucet valves that are used today in the home and elsewhere have a movable valve stem that carries a valve surface for opening and closing a valve port to allow water to enter the faucet. Commonly, such valve stems move vertically by reason of a screw thread arrangement cooperative between the valve stem and a gland nut or housing that mounts the valve stem in the faucet or valve housing. The faucet handle is attached to the valve stem and rotation of that handle causes the valve stem to be moved between open and closed positions. In order to prevent the passage of water between the valve stem and the gland nut, it is common to provide a seal between the gland nut and the valve stem. In most instances, this seal is a conventional elastic, rubber or neoprene O-ring.
After the faucet has been used for several years, it is common for the O-ring to deteriorate or wear to the point where the O-ring no longer provides an adequate seal and water will leak past the O-ring and up the valve stem and flow from the faucet housing, thereby wasting water and requiring frequent clean-up.
In order to replace the O-ring, the gland nut is removed from the faucet housing, the old O-ring removed and another installed in its place. However, much time is spent in applying the O-ring because the bottom portion of the valve stem usually forms a laterally extending washer cup or valve surface and the O-ring must be stretched over this cup or surface and thereafter positioned in a retaining groove in the valve stem. This can be a time-consuming and frustrating experience for the installer because many times difficulties are experienced in stretching the O-ring sufficiently to have it pass over the end of the valve stem.
Conical surfaces for stretching and applying O-rings, usually under industrial conditions, have been previously proposed. However, such apparatus are not suitable for use by people in the field, such as plumbers, for replacing or refitting O-rings.